A virtual router redundancy protocol (VRRP) is a protocol for providing redundancy of nodes in networks. In a VRRP, one of a plurality of nodes belonging to a specific VRRP group is defined as a master node (that is, a current-in-use node) and the other nodes are defined as backup nodes (that is, standby nodes). Normally, only the master node performs processing. When a failure occurs in the master node, one of the backup nodes takes over the processing.
One virtual media access control (MAC) address and one virtual internet protocol (IP) address are assigned to each VRRP group. In a network using a VRRP, settings for switches and the like in the network are performed in such a manner that data whose destination addresses are the virtual MAC address and the virtual IP address is transferred to the master node.
A related art is described, for example, in Japanese National Publication of International Patent Application No. 2010-518710.